Grinding wheel truing apparatus



Feb. 13, 1940, A c. c. ALVORD 2,190,132

GRINDING WHEEL TRUING APPARATUS Feb. 13, 1940. l c. c. ALvoRD l2,190,132

` GRINDING' WHEEL TRUING APPARATUS Filed July 2, 1938 Sheets-Sheet 2 CH-ARL Es C'. A L 'VDRJJ @www am,

Feb. 13, 1940. Q C, ALVORD 2,190,132

GRINDING WHEEL TRUING APPARATUS Filed July 2, 1958 3 Sheets-Sheet 5 CHARLES C. ALVURD Patented Feb. 13, 1940 "Charles C. Aivord, Worcester, Mass., assignor to orten CompannWorcestcr, Mass., a corpora- `tion of Massachusetts Application July 2, 1938, Serial Noe. 217,289

4 Claims.

The invention relates to grinding machines, and more particularlyto a grinding wheel truing apparatus therefor.

One object of: the invention is to provide a. sim- 6 ple and thoroughly practicalgrlnding wheel tru# ing apparatus.V A further object of the invention is to provide an hydraulically actuated grinding wheel truing apparatus. A further object of the invention is to provide a truing apparatus-with an l hydraulically reciprocated truing apparatus for a grinding machine. f A further object -of the invention is to provide an hydaulically operated feeding mechanism'for adjusting the position of the truing tool. A further object of the invention is to provide a remote electrical control for starting and stopping the operation of an hydraulically operated wheel truing apparatus. A further object of the invention is to provide a remote electrical control mechanism for controlling the hy draulic reciprocation o1 the truing tool. Another object of the invention is to provide a remote electrical control mechanism for controlling the feed of the trung tool. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements and arrangements of parts, as will be exemplified in the structure to be hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings in which is shown one of various possible embodiments of the mechanical features of this invention:

Figure 1 is a. front elevation of a grinding wheel slide, showing the improved grinding wheel truing apparatus mounted thereon;

Figure 2 is a right-hand end elevation of the wheel slide and truing apparatus shown in. Figure 1;

4o Figure 3 is a fragmentary rear view of the upper portion of the wheel trulng apparatus, showing the forming bar and follower roll;

Figure 4 is a diagrammatic illustration of the piping for the hydraulic system and hydraulic controls as well as an electrical diagram showing the electrical controls for the hydraulic mechanism;

Y Y Figure 5 is a cross sectional view, on an enlarged scale, taken approximately on the line 6--5 of Figure 2;

Figure 6 is a vertical cross sectional view, taken approximately on the line 6--6 of Figure 1, showing the pivotal support for the truing apparatus;

Figure 'l isa vertical sectional view, on an enlarged scale, taken approximately on the line 'l-T a of Figure 3; Figure 8 is a fragmentary elevation. partly broken. away and shown in section, on an enlarged scale, of the load and re reverse lever mecha- 5 nism;

s Figure 9 is a fragmentary sectional view, taken approximatelyon the line 9-9 of Figure 8;

Figure 10 is a fragmentary plan view, .taken approximately on the line Iu--lll of Figure 3, 10 on an enlarged scale showing the forming bar and the adjustment therefor;

Figure 11 is lva. longitudinal sectional View through the forming bar, taken approximately on the line II'-li of Figure 10; and

lFigure 12 is a sectional view, taken approximately on the line I2-I2 of Figure 11, showing the forming bar and the follower roller.

As illustrated in the drawings, a transversely movable grinding wheel slide 20 is provided with 20 the usual V-way 2l and iiat way 22 which mate withy .correspondingly shaped ways on the base (not shown). The wheel slide 20 supports in bearings (not shown), a rotatable wheel 'spindle 23 which supports a grinding wheel 24 adjacent 25 vto its left-hand end (Flg. 1). The wheel spindle i 23 may be rotated in any suitable manner, such as is old and well known in the art. In the preferred construction, however, an electric. motor 26 is adjustably mounted on the upper surface 30 of the wheel slide 20. 4 The motor 25 has an arma ture or rotor shaft 23 on the end of which is vmounted a multiple V-grooved pulley 21 which is connected by multiple V-belts 28 withv a multigrooved4 pulley 28 mounted on the right-hand end 35 of the wheel spindle 23 (Fig. 1).

The wheel slide 20 is mounted on the grinding machine so that it may be fed transversely to feed the grinding wheel 24 into the work piece to grind the same to the required extent. The wheel slide o 20 is provided with a depending half nut 30 which meshes with a rotatable feed screw 3| which is rotatably supported in the base ot the machine. Thefeed screw Il may be rotated by any of the well known feeding mechanisms, such as, for ,I example, that shown inthe prior United States patent to C. H. Norton No. 762,838 dated June 14, 1904. The improved trulng apparatus is preferably mounted on the wheel slide 20 so that it travels 50 forward and rearward with the wheel slide during the grinding operation and the diamond or truing tool is at all times maintained in a predetermined position with relation. to the grinding wheel 24. A truing apparatus frame 36 is preffl erably pivotally mounted on the. wheel slide 20 so that it may be angularly adjusted in a vertical plane so that the path of movement of the truing tool is parallel to or at an angle to the axis of the wheel spindle 23. The wheel slide 20 is yprovided with a pair of spaced brackets 36 and 31 which support a shaft 38. The frame 35 is provided with the downwardly projecting portions 39 and 40 having apertures rotatably to receive the shaft 38 and thereby provide a pivotal connection between the frame 35 and the wheel slide 20. A pair of screw threaded studs 4| and 42 are flxedly supported in an upper surface of the wheel slide 20 (Figs. 1 and 2). The studs 4| and 42 pass through clearance holes in a pair of lugs 43 and 44 which project from the frame 35. Nuts are provided on each of the studs 4| and 42 above and' below the lugs 43 and 44, respectively. By manipulation of these nuts, the frame 35 may be adjusted in a vertical plane to adjust the path of movement of the truing tool, as will be hereinafter described.

The frame 35 is provided with a horizontal extending dovetailed slide 45 which is either formed integral with or xedly secured to the frame 35. A horizontally movable slide 46 is provided with a-dovetailed slideway which mates with the dovetailed slide 45. The horizontally movable slide 46 is provided with an upwardly extending member 41 which is provided with a vertically arranged dovetailed slideway 46. A vertically movable slide 49 is provided with a dovetailed slideway which mates with the dovetailed way 48. The lower end of the vertical slide 49 is provided with a forwardly projecting boss 50 which supports a bar 5| which carries a truing tool or diamond 52 `at its outer end to true the peripheral face of the wheel 24 when the horizontally movable slide 46 is reciprocated.

In `the preferred form, an hydraulically operated mechanism is provided for reciprocating the horizontally movable slide 46 to traverse the truing tool 52 across the operative face of the grinding wheel 24 to true the same. `A fluid pressure cylinder 55 is preferably formed integral with the frame 35. A piston 56 is slidably mounted within the cylinder 55 and is connected to one end of a piston rod 51 the other end of which is connected to a bracket 58 xedly mounted on the end of the horizontally movable slide 46. It will be readily apparent from the foregoing disclosure that when uid is admitted either into the cylinder chamber 59or the cylinder chamber 60, the piston 56 and piston rod 51 will transmit a traversing movement to the horizontally movable slide 46 and the truing tool 52. Y

A uid .pressure system is provided for conveying fluid under pressure to reciprocate the truing tool, comprising a motor driven fluid, pressure pump 6| which draws uid from a reservoir 62 through a pipe 63 and forces uid through pipe 64 and pipe 65 to a truing tool traverse control valve 66. The control valve 66 is mounted on the steadyrest frame 35. Fluid under pressure from the pipe 64 also passes through a pipe 61 to a truing tool feed control valve 68 to be hereinafter described.

The truing tool traverse control valve 66 comprises a valve stem 69 having formed integrally therewith valvepistons 10, 1|, 12, 13 and 14. In the position of the valve 66 (Fig. 4), fluid under pressure within the pipe 65 passes through a pipe 15 into a valve chamber 18 formed between the valve pistons 12 and 13 and passes out through a pipe or passage 11 into the cylinder chamber control knob 86.

60 to cause the piston 56, the piston rod 51, and the horizontally movable slide 46 to traverse toward the left to pass the truing tool 52 across the periphery of the grinding wheel 24. During this movement, uid within the cylinder chamber 59 is forced out through a pipe or passage 18 into a valve chamber 19 formed between the valve pistons 1| and 12 and passes out through a pipe or passage to a feed control valve 8| which regulates the rate of exhaust of fluid from the chamber 55 and thereby controls the traversing speed of the truing tool 52.

The controlvalve 8| is provided with .a valve stem 82 having a body portion which fits Within the valve sleeve and is provided with a V-shaped notch 83. The V-shaped notch 83 is normally held in a rearward position to prevent the exhaust of fluid from the pipe 80 by means of a spring 84 which surrounds the valve stem 82 and is interposed between the end of the valve casing 8| and an adjustable collar 85 threaded on the end of the valve stem 82. A manually operable knob 86 is mounted on the outer end of the valve stem 82 and serves to facilitate manual adjustment. The valve 8|, in addition to serving as a speed control valve, serves as a stop and start valve for the traversing movement. When it is desired to start the traverse of the truing tool 52, the Valve stem 82 is moved manually or automatically toward the left so that the V-notch 83 assumes the position illustrated in dotted lines 83a, so that fluid exhausting through the pipe 80 may flow through the V-notch 83 out through a port 81 and a passage 88 into a pipe 89 which exhausts into the reservoir 62. In order to regulate the speed of movement of the truing tool 52, the valve stem 82'may be rotated to vary the position of the V-shaped notch 83 and thereby to vary the exposed aperture of the port 81 so as to regulate the amount of fluid exhausting through the pipe 80 and thereby to control the speed of movement of the truing tool 52. To facilitate holding the valve stem 82 in adjusted position, the

valve stem is provided with a serrated portion 90 which is engaged by a spring-pressed plunger 9| carried by the casing of the valve 8|, so that when the valve stem 82 is rotated by means of the knob 86, the spring-pressed plunger 9| engaging the serrations of the portion 90 will serve to hold the valve stem 82 in adjusted position but at the same time permit a longitudinal movement of the valve to stop and start the traversing movement of the truing tool 52.

The valve 8| may be operated manually, if desired, by means of the knob 86 or may be operated automatically by an electrically operated mechanism. The valve stem 82 carries a spool shaped member havingv a groove 96. A pair of diametrically opposed pins 91 carried at the lower yoked end of the rock arm 98 (Fig. 4) ride in the groove 96. The rock arm 98 is pivotally supported on a stud 99 which is xedly supported on a bracket |00 which is xedly supported on the solenoid |05. The upper end of the rock arm 98 (Fig. 4) is connected by a stud |0| with a link |02. The other end of the link |02 is connected by a stud |03 with an armature |04 of the solenoid |05.

In a large cylindrical grinding machine of the type illustrated, due to the massive size of the machine, it is diicult for the operator to reach up over a large work piece and readily* reach the It is, therefore, desirable to provide a remote control apparatus including a switch |06 which is operated by a pair of push buttons |01 and |09. Power for the circuit is |33 formed in the lower ,surface of the projecsupplied as represented by the power lines |09 which are connected as illustrated with the 4switch |06 and the solenoid |05. In the position of the switch |06 as illustrated in Fig. 4, the circuit is open and the solenoid |05 deenergized. When it is desired to start the traversing movement of the truing tool 52 from thevoperator's station in front of the machine to true the grinding wheel 24, the push button |01 isactuated to shifto the switch member |06 into the position |06a illustrated in dotted lines in Fig. 4 to close the circuit, thereby energizing the solenoid |05 which in turn serves through the connecting link |02 to rock the rock arm 98 in a clockwise direction to shift the valve stem 82 toward the left and thereby move the V-notch 83 into the dotted line position 83a to allow fluid to exhaust through the pipe 80 at a controlled rate.

A reversing mechanism is provided automati- .cally to shift the traverse control valve 66 con` tinuously to reciprocate the truing tool 62 across the face of the wheel 24 as desired. A rock arm ||5 is rotatably supported on a sleeve ||6 which isin turn rotatably supported on a stud ||1. The stud ||1 is ilxedly mounted in a boss ||8 which is formed integral with the frame 36 of the truing apparatus. vThe upper end of the rock arm ||5 is provided with a pin ||9 which rides within a groove |20 formed in a spool shaped member |2| mounted on the right-hand end of the valve stem 69 (Fig. 4). A reversing lever |22 is xedly mounted o n the outer end of the sleeve ||6. 'Ihe upper end of the reversing lever |22 is provided with a stud |23 which is arranged in the path of adjustable dogs |24 and |25. The dogs |24 and |25 are adjustably supported in a T-shaped slot |26 formed in a projection of the horizontally movable lslide 46. The sleeve ||6 is provided with a downwardly extending arm |21 which is provided at its lower end with a pair of opposed spring-pressed plungers |26 and |29 which are arranged to engage the opposite sides of a projection |30 formed on the lower end of the rock arm ||5. The tension of the springs which actuater the plungers |28 and |29 may be adjusted by means of the threaded sleeves I3| and |32, respectively. 4The spring pressed plungers together with the mechanism above described serve as a load andl nre mechanism whereby the control valve 66 is automatically reversed in timed relation with the traversing movement of' the horizontally movable slide 46.

In cylindrical grinding operations it is frequently necessary to provide a machine which may either grind a true cylindrical surface, a tapered surface, or a cUurved lface for grinding a curved surface on the periphery-of a work piece. It is accordingly one object of this invention to provide a truing apparatus which may bue adjusted for truing a true cylindrical face on the grinding wheel 24, or a tapered face thereon, or if de-A sired a curved face. In the preferred form.' the vertically extending projection 41 o f ,the horizontally movable slide 46 is provided with a dovetailed slideway on its rear face which supports a v vertically movable slide |33 having a dovet'ailed slideway.y |34 mating With the dovetailed slideway on the member 41.4 The lower end of the slide |33` is provided with a rearwardly extending'portion l supported on a stud |4| on the truing apparatus frame 36 and is held in position thereon by clamping blocks |42 and |43.r The forming bar |39 is arranged so that the axis of curvature of the partially cylindrical surface |40 is parallel to the path of movement of the truing tool 52 and the axis of the grinding wheel 24 to true a true cylindrical face on the grinding wheel 24, or the .bar |39 may be swivelled so that the axis of curvature of'the partially cylindrical surface |40 is at an angle to the axis of the grinding wheel 24 and the path of movement of the truing tool 62. In the latter case, when the horizontally mov` able slide' 46 is traversed longitudinally, the roller |36 engaging the surface |40 of theforming bar |39 "is moved in a vertical direction to move the truing tool or diamond 52 through a curved path as its supporting I'slide 46 is moved horizontally.

To facilitate angular adjustment of the forming bar |39, the left-hand end is provided with a segment of a gear |44 (Fig. 10) which meshes with a rotatably mounted pinion |46. By loosening the clamping blocks |42 and |43 and turning the pinionv |46 by means of a screw driver or other similar instrument placed in the slot formed in the upper end face of the stud supporting the pinion |45. the forming bar |39 may be readily-adjusted into the desired position and then locked in, adjusted position by means of the clamping blocks |42 and |43. The left-hand end face of the forming bar |39 may be provided' with a graduated scale to facilitate readily adjusting the bar to the desired predetermined position. o The vertically movable slides 49 and |33 are preferably arranged so that they both move vertically and simultaneously as controlled by the follower roller |36 and the forming bar |39.

The two slides are preferably connected by a vnut and' screw. mechanism whereby the position of the truing tool 62 may be readily adjusted both in setting up the machine and also in ad-v justing or feeding the truingtool during a truing operation. The slide |33 is provided with a for- ,wardly extending boss |46 which rotatably supports a vertically arranged feed screw |41 which in turn passes down through the slide 49 and meshes with a nut |48 which is secured to lthe slide V49. The upper end of the screw |41 is journalled in suitable anti-friction bearings within the boss |46 so that it is held againstl endwise movement relative to the slide |33. It will be readily apparent from the lforegoing that the (slide |33 is interconnected with or adjustably connected to the slide 49 by means of the boss us, the feed screw M Laiid the nur ua.

To facilitate adjustment of the feed screw |41, a manually operable hand wheel andoI pawl and ratchet mechanism. are provided/wlereby the screw |41,1'nay be either rotated manually or actuated mechanically by means of a pawl and ratchet mechanism.' A bracket |60 is rigidly ,mounted on the rear face of the slide |33 and .serves as a support for a housing |6| for the truing tool feeding mechanism. A shaft |52 is rotatably supported by the housing 6| and carries at its lower end a gear. |63 which meshes with a gear |64 mounted on the upper end of the feed screw |41. The upper end of the shaft |52 projects above the casing |5| and is provided on its upper end with a manually operable hand Wheel |55. By rotation of the hand wheel |55, a. rotary motion is transmitted to the shaft |52, the gear |53, the gear |54, and thel feed screw |41 to adjust the .position of the slide 49 relative to the slide |33, so as to position the truing tool 52 as desired. The weight of the slides 49 and |33 combined with the feeding mechanism above described is sufficient weight at al1 times to maintain the follower roller |36 in operative engagement with the operative surface |48 of the forming bar |38 so that when the horizontally movable slide 46 is traversed for a truing operation, the follower roller |36 will follow the contour of the forming bar |39 as then adjusted.

In a large cylindrical grinding machine, such as is used for grinding large massive rolls and the like, a truing apparatus of this type is out of the reach of the operator and it requires his climbing on top of the machine manually to adjust the position of the truing tool 52. It is desirable in such a case to provide a suitable remote control apparatus whereby the truing tool may be readily adjusted and fed from the operators control station. In the preferred form, a pawl and ratchet mechanism is provided .Comprising a ratchet wheel |56 which is keyed to .the shaft |52. A ratchet pawl |51 is pivotally supported on a pawl carrying bracket |66 rotatably.

supported on a cylindrical hub portion of the' ratchet wheel |56. The pawl carrying bracket |58 is provided with an outwardly extending arm |59 which is arranged between a pair of opposed screws |60 and |6| which serve to limit the movement of the pawl |51 and consequently the ratchet wheel |56. A stop pin |62 carried by the frame |58 serves to limit the movement of the pawl |51 in a clockwise direction. A spring pressed plunger |58a, carriedby the hub of the pawl carrying arm |58` bears against the hub of the ratchet wheel |56. The plunger |58a serves as a friction device to retard movement of the arm |58 and thereby insure the disengagement of the pawl |51 from the ratchet wheel |56 before the arm |58 starts moving. The pawl |51 is pivotally supported on a stud |63 and is preferably forrned as a bell crank having an outwardly extending arm |64 which is connected to an actuating link |65. y

In the preferred form, the pawl and ratchet mechanism is actuated by a hydraulically operated mechanism comprising a cylinder |66 having aV piston |61 slidably mounted therein. A spring |68 surrounds a piston rod |68 projecting from the piston |61 and is interposed between the piston |61 and a bracket |10 carried by the housing |5|. The spring |68 normally holds the piston |61 in a position so that th`e arm |59 engages the stop screw |6| and the ratchet pawl 514 is" withdrawn to an inoperative position in engagement with the stop pin |62. When fluid under pressure is admitted through a pipe |1| into the cylinder |66, it causes an upward movement of the piston |61 (Fig. 4) against the compression of the spring |68 which rst serves to rock the pawl |51 in a counterclockvvi'se direction into operative engagement with the teeth of the ratchet wheel |56, and continued movement rotates the ratchet wheel |56 until the projection |59 of the pawl carrying member |58 engages the stop screw |60 which limits the feeding 'movement.

The admission of fluid under pressure to the pipe 1| is controlled by the feed control valve 68. This valve is preferably a piston type valve comprising a valve stem |12 having formed integrally therewith valve pistons |13 and |14. A spring |15 surrounds the valve stem |.12 and is interposed between the valve piston |13 and the end cap on the valve casing and serves normally to hold the valve stem |12 and valve pistons |13 and |14 in a right-hand end position (Fig. 4) so that fluid under pressure from the pump 6| passing through the pipe 61 enters a valve chamber |16 located between the valve pistons |13 and |14 and passes out through the pipe |1| into the cylinder |66 to actuate the diamond or truing tool feeding mechanism.

In order that the truing tool 52 may be fed by means of a remote control, a solenoid |18 is provided having an armature |19 connected by a link |86 with the valve stem |12. In the position of the parts illustrated in Fig. 4, uid within the cylinder |66 may exhaust through the pipe |1l, the valve chamber |16, and out through a pipe |8| into the reservoir 62. A push button switch |02 is mounted on the front of the machine base adjacent to the operators station. This push button switch is operatively connected between the power llines |09 and the solenoid |18. When the push button |82 is actuated, it serves to close a circuit, thereby energizing the solenoid |18 to shift the valve stern |12 toward the left (Fig. 4) so that fluid under pressure passing through the pipe 61 enters the valve chamber |16 and passes out through the pipe |1-| into the cylinder |66 to actuate the pawl and ratchet mechanism. and thereby feed the truing tool 62 one increment toward the periphery of the grinding wheel 24 to be trued. As soon as the operator removes his hand from the push button |82, the switch opens and the circuit is broken, thereby deenergizing the solenoid |18, and the released compression of the spring |15 shifts the valve into its right-hand position, as shown in Fig. 4, so that the fluid within the cylinder |66 may exhaust into the reservoir 62. It will thus be seen that from the operators control station in front of the machine, the truing tool may be incrementally fed toward the grinding wheel at the will of the operator and the tool may be advanced by one or more increments as desired.

The operation of this improved truing apparatus will be readily apparent from the foregoing disclosure. Assuming the mechanism to have been previously adjusted, that is the dogs |24 and |25 adjusted for length of stroke, the stop screws |60 and |6| adjusted to regulate the incremental diamond feeding, and the valve 8| adjusted to traverse the truing tool 52 at the desired and predetermined speed, the grinding wheel 24 may be readily trued and its movement controlled by the operator from his control station in front of the machine. When it is desired to true the grinding wheel 24, the operator presses the button |01 to close the switch |06, that is, shifts it into position |06a which serves to energize the solenoid |05, thereby rocking the rock arm 98 in a clockwise direction to open the valve 8| and thereby start the reciprocating movement of the horizontallygmovable slide 46. During the reciprocating movement of the horizontal slide 46 and the truing tool 52, the truing tool may be incrementally fed toward the periphery of the grinding wheel 24 by one or more increments by closing the push button switch |82 to energize the solenoid |18 and thereby open the valve 68 to actuate the feed pawl |51 through one increment. When the operator releases the push button |82, the solenoid |18 is deenergized and the valve 68 returns to its initial position, thus allowing i'luid within the cylinder |66 to exhaust and the released compression of the spring |68 rocks the feeding pawl |58 into an inoperative position (Fig. 4) ready for the next feeding movement. By actuating the push 'button |82 either at the ends of the reciprocatory stroke of the truing tool 52 or intermediate therebetween, the tool may be readily fed to true the desired amount olf the periphery of the `grinding wheel 24.

It will thus be seen that there has been provided by this invention apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodis'ments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

l. In a grinding wheel truing apparatus, a truingtool, means including a piston and oylinderk longitudinally to reciprocate said truing tool, means including a dog actuated reversing valve to control the admission of fluid to said cylinder, a stop and start valve operatively connected to control the exhaust of uid from said cylinder, a remote control therefor including a solenoid to actuate said valve, a remotely located switch to actuate said solenoid, means including a iluid pressure operated pawl and ratchet mechanism to feed said tool transversely, a control valve therefor, and a remote electrical control for said feed valve including a solenoid to actuate said valve, and a remotely located push button switch to control said valve whereby the tool may be incrementally fed transversely as desired.

' 2. In a grinding wheel truing apparatus for a grinding machine having a wheel slide to support a rotatable grinding wheel, an adjustably mounted truing apparatus frame on said slide, a longitudinally reciprocable slide on said frame, `means to adjust said frame relative to said slide to adjust the path of movement of said truing tool, a transversely movable slide on said horizontal slide, a truing tool supported thereon, means including a uid pressure operated piston and cylinder longitudinally to reciprocate said horizontal slide, means including a dog actuated reversing valve supported on said frame and arranged to control the admission of iluid to and from said cylinder, a combined stop-startthrottle valve on said frame to control the exhaust of fluid from said cylinder, means to rotateI said valve to regulate the speed of said truing tool, a remote electrical control for said latter valve including a solenoid to move said valve endwise to stop or start the traverse of sai-d truing tool, and a remotely located switch to operate said solenoid.

3. In a grinding wheel truing apparatus fora grinding machine having a Wheel slide supporting a rotatable grinding Wheel, a truing apparatus frame pivotally supported thereon, a horizontally movable slide on said frame, a vertically movable slide on said horizontal slide, a truing tool carried by said vertical slide, means pivotally to adjust said frame to Vary the position of said horizonal slide relative to the wheel axis to vary the path of movement of the truing tool, means Ito adjust said vertical slide relative to said horizontal slide to feed the truing tool toward or from the grinding Wheel, means including a i'luid operated piston and cylinder longitudinally to reciprocate said truing tool, a dog actuated reversing switch to control the admission to a'nd exhaust of fluid from said cylinder, a combined stop-start-throttle valve to control the exhaust-of iluid from said cylinder and to regulate the truing speed of said tool, a solenoid operatively .connected to actuate said latter valve, and a remote electrical control therefor including a remotely located switch to operate said solenoid.

4. In a grinding wheel truing apparatus for a grinding machine having a wheel slide and a rotatable grinding wheel, la pivotally mounted truing apparatus frame on said slide, a horizontally movable slide on said frame, a vertically movable slide on said horizontallymovable slide, a truing tool carried by said vertical slide, means including a iluid pressure piston and cylinder to reciprocate said horizontal slide so as to traverse the truing tool across the periphery of the grinding wheel, means including a solenoid operated yvalve to stop and start the reciprocating movement of said slide, a remote electrical control including a remotely located switch to energize said solenoid, and means including a. fluid pressre operated pawl and ratchet mechanism to feed said vertical slide relative to said horizontal slide, means including a valve to control l trol therefor including a remotely located switch to energize said solenoid so as to cause an incremental feeding movement of the truing tool when desired.

CHARLES C. ALVORD. 

